Top: position-velocity diagrams of CO v = 2–1 from HD 100546. All vibrational transitions of CO v = 2–1 in our observational coverage that do not overlap with the deep absorption lines of the terrestrial atmosphere are registered and added. The spectra were recorded with the slit PA = 145° (left) and 325° (right). The spatial axis is in abscissa with the position angles to which the slit was aligned indicated by arrows. The line image obtained with slit PA = 325° is flipped horizontally so that the offset from the central star increases to the right in both of the line images. The continuum emission of the star was interpolated from both sides of the line emission and subtracted. The contours are drawn at every 10% of the peak brightness, except the lowest one which is at 5%. The apertures of the spectral extraction are marked by rectangles. Faint emission is still visible at 50 AU away at low velocity. The sizes and the locations of the extraction apertures are summarized in Table 1. Bottom: spatial profile of the line emission, i.e., the position-velocity diagram shown in the upper panels are crushed along the velocity space.